Extruded and Labelled Packaging Tube

ABSTRACT

The invention relates to a method for the extrusion and labelling of a packaging tube ( 14 ), comprising the following successive steps performed on an extrusion-labelling line, namely: a) forming a partially or fully tubular label ( 17 ) from a film ( 12 ); b) introducing the label ( 17 ) into a calibration element ( 22 ); c) extruding a tubular body ( 13 ) on the side of the concave surface of the label ( 17 ); d) bringing the external surface of the tubular body ( 13 ) into contact with the concave surface of the label ( 17 ), step (c) being performed in the calibration element ( 22 ). The invention also relates to an extrusion-labelling device and a packaging tube.

FIELD OF THE INVENTION

The invention relates to the field of tubes or cylinders, and morespecifically to packaging tubes for viscous or liquid products in whichthe skirt is obtained by extrusion.

PRIOR ART

Flexible packaging tubes usually have two separate portions,specifically a skirt or flexible cylindrical body linked to a headcomprising a neck and closed by a cap. The skirt of the tube is obtainedby extrusion of a tubular body, or by welding a multilayer sheet.

There are numerous methods for adding the tube head to the end of apreviously extruded skirt. The tube head may be molded by compression orinjection and jointly welded to the skirt by overmoulding. Anothermethod involves prefabricating the tube head by injection or compressionmolding, then assembling the tube head on the skirt by welding.

The tube thus formed is then decorated around the skirt. In some cases,the printing operation is carried out before assembly of the skirt andthe tube head. This printing operation has several drawbacks related tothe fact that the printing is not carried out flat but on the tubularshape of the skirt. This usually requires a more complex method and,consequently, costly equipment, slower production speeds and reducedflexibility. The limited flexibility of printing machines for examplerequires repeat operations for complex decorations such as screenprinting or hot decoration.

In order to overcome decoration difficulties, a method involves applyinga preprinted adhesive label. The label is related to a carrier film,usually made of PET, and is separated from the carrier duringapplication to the outer surface of the tube. The label is pre-coatedwith a sticky adhesive that binds the label to the surface of the tube.The adhesive layer is protected by the carrier film before the label isapplied to the tube.

The method disclosed in patent application WO 2007/092652 involvesapplying a thin label that is not stuck to a carrier film before use.According to this method, the spreading or activation of the adhesivelayer takes place at the time the label is applied to the surface of thetube. A variant of this method involves applying the adhesive layer tothe label at the time of application. Another variant involves applyingthe adhesive layer to the surface of the tube before application of thelabel. However, the method described in WO 2007/082652 has a number ofdrawbacks. The addition of an adhesive layer by spreading at the time ofapplication of the label or the addition of an activation step makes themanufacturing process more complex, in particular when applied to acontinuous tube extrusion line (FIG. 2 in WO 2007092652). Anotherdrawback relates to the very short activation times of the adhesivelayer required by this method, which may limit the choice of adhesivesto costly adhesives. Another drawback relates to the packaging: a labeladded to the surface of the tube is not an integral part of the wall ofthe packaging. The edges of the label are sometimes visible ordetectable to the touch and have an adverse effect on the decoration andaesthetic qualities of the packaging.

Patent application EP 0 457 561 A2 discloses a method and a device forproducing extruded tubular bodies with a laminated film on the surface.This method involves forming a first tubular body from a film, extrudinga lining member inside said tubular body, drawing the lining memberradially and pressing the lining member against the tubular body. Thismethod has several drawbacks. A first drawback is related to the factthat the lining member has to be extruded inside the tubular body formedby the film. This operation requires the tube diameter to be largeenough to allow the tools required for extrusion and radial drawing ofthe extruded lining member to be inserted into the tube. The methodproposed in this prior art document does not enable the manufacture ofsmall-diameter tubes, in particular tubes with a diameter of less than35 mm. EP 0 457 561 A2 also proposes the internal calibration of thediameter of the tube. In addition to the issues of size mentioned above,this method has the drawback of generating small variations in theexternal diameter of the tube. These variations, which depend on theregularity of the flow rate from the extruder, may result in decoratingdefects. Indeed, to obtain high-quality decoration, the ends of thedecorative film on the outer surface of the tubular body must be fittedend to end. Variations in the extrusion rate mentioned above result invariations in the external diameter of the tubular body, therebyincreasing or decreasing the distance between the ends of the decorativefilm. Such variations result in visual defects at the join between theends of the decorative film.

Similar drawbacks are found in the methods and devices described inpatent applications DE 1 504 918 and DE 10 2006 006 993.

There is therefore a need to overcome the aforementioned drawbacks.

DEFINITIONS

In the present text, the term “labeling” shall refer to the attachmentof a film, also referred to as a “decorative film” or “label”, to atube.

The term “decoration” refers to a visual element used for informationand/or aesthetic purposes.

SUMMARY

The invention relates to a method, a device and a tube, as defined inthe claims.

The invention enables the decoration of extruded tube skirts using acheap and flexible method. It involves combining extrusion operationswith labeling operations to form a decorated tubular body. The label maybe a single-layer or multilayer decorative film. The decorative film isincorporated into the packaging during extrusion when the tubular bodyis in the molten state, such that the outer surface of the decoratedpackaging forms a continuous surface with no roughness. In the methodaccording to the invention, the decorative film is an integral part ofthe packaging, unlike a normal label which would be added to apreviously formed package.

Preferably, the decorative film that forms all or part of the outersurface of the tubular body is welded to the tubular body by the heat ofthe extruded resin. According to one embodiment, the decorative filmcomes into contact with the molten extrudate before the cooling phaseand before the calibration step.

The method according to the invention results from the combination of anextrusion method and a labeling method. The method involves bringing thelabel into contact about the tubular body in the molten state,preferably after the operation to form the tubular shape of the film.Advantageously, the resulting multilayered tubular structure iscalibrated and cooled in order to obtain a decorated extruded tube.

According to a preferred embodiment of the invention, the methodcomprises a first step in which the film is formed into a partially ortotally tubular shape, followed by a second step in which a tubular bodyin the molten state is extruded, followed by a third step in which theouter surface of the tubular body in the molten state is brought intocontact with the (concave) inner surface of the label, and finally afourth calibration step in which the outer surface of the label intendedto form the outer surface of the tube is applied onto the internalsurface of the gauge. The third step is performed using a pressuredifference between the inner and outer surfaces of the tubular body. Thefourth step is performed using a pressure difference between the innersurface and the outer surface of the tube.

The method according to the invention involves manufacturing an extrudedtubular body having a decorative film label that, in a preferredembodiment, forms the entire outer surface thereof. In this preferredembodiment, the tubular body is entirely enveloped by the label whensame passes through the gauge and the successive cooling tanks. Themolten material does not rub against the cooled tools, which helps toimprove the aesthetic appearance of the packaged products, and theresistance of same to impact and stress cracking.

According to a variant of the invention, a first pressure difference isused to bring the tubular body and the label into contact. This firstpressure difference is exerted at least between the outlet of theextrudate from the nozzle of the tool and the contact zone between theinner surface of the film and the outer surface of the extrudate. Thisfirst pressure difference helps to prevent the formation of air bubblesbetween the label and the outer surface of the tubular body. Accordingto one embodiment of the invention, the pressure difference is createdby a positive air pressure inside the tube. An alternative embodimentfor creating this pressure difference involves creating anegative-pressure chamber between the extruder and the calibrationelement. According to one embodiment, the tubular body and the label arebrought into contact with one another immediately after formation of thefilm into a tubular shape.

According to a variant of the method, the film is formed into a tubularshape at the same time as the tubular body is inflated onto the innersurface of the film. According to this variant, the contact plane (theplane formed by the contact zone) between the film and the tubular bodyis inclined in relation to the axis of the tube, unlike in the prior artwhere the contact plane is always perpendicular to the axis of the tube.

Advantageously, a second pressure difference is exerted to press theouter surface of the tube against the inner surface of the calibrationelement, thereby preventing retraction of the tube during cooling. Thiscalibration step helps to precisely adjust the external diameter of thetube. In the method according to the invention, the outer surface of thetube is formed by the label sliding onto the inner surface of the gauge.The tube is then cooled and cut using the conventional methods.

The label is preferably thin compared to the thickness of the extrudedtubular body.

The label may be a multilayer film. When same is brought into contactwith the extruded body in the molten state, the surface of the filmforming the interface with the tubular body is heated to a temperatureenabling said tubular body to be welded to the decorative film.According to the preferred embodiment, all of the heat required forwelding is provided by the tubular body. On account of the thinness ofsame, the label is cooled on the (convex) outer surface of same at thesame time as the welding operation. Cooling is effected by contact ofthe outer surface of the label with the inner surface of the gauge or bycontact with water. Cooling the label at the same time as the weldingoperation helps to preserve the quality of the decoration as well as thesurface properties of the label (gloss, matte effect, roughness, etc.).

Advantageously, the label is incorporated into the thickness of thepackaging and covers the entire outer surface of the tubular body.

According to another embodiment of the invention, the label is onlyformed on a portion of the circumference of the tubular body, the edgesof same being contained by the resin extruded such that the outersurface of the tubular body forms a continuous surface.

The label may provide the packaging with decoration. The label may alsoprovide the packaging with surface properties modifying the “feel” ofsame. In this regard, the invention makes it possible to provide thesurface of the packaging with other materials that are impossible ordifficult to extrude, such as paper, textiles, soft-touch resins, etc.

The label is advantageously used for the barrier properties of same.This embodiment obviates the need to use a co-extrusion device for thetubular body.

Another advantage of the invention is to facilitate the extrusion ofresin grades that are difficult to extrude as a result of being liableto stick-and-slip phenomena during calibration, or to surface defects,or to extrudate breakage.

More generally, the invention may be used to increase productivity sincethe molten material is no longer in direct contact with the surface ofthe gauge. The friction between the molten material and the calibrationelement found in a conventional extrusion method is eliminated, therebyenabling production speed to be increased.

The packaging resulting from this manufacturing method ensures verystrong cohesion between the label and the tubular body. The risk of thelabel coming unstuck during use of the packaging is eliminated, unlikethe packaging in the prior art that is produced using an adhesive label.Another advantage relates to the absence of any discontinuities on thesurface of the tubular body, which helps to prevent problems related tolabels, sections of which can accumulate dust, thereby adverselyaffecting the aesthetic properties.

The invention also makes it possible to produce decorated tubes of smallor large diameter. The invention is very flexible and may be used in newfacilities or to modify existing extrusion facilities.

The invention also comprises an extrusion/labeling device, as describedin the claims. The device produced according to a preferred embodimentincludes means for extruding a tubular body in the molten state, avacuum cooling and calibration tank, means for conveying the cooledtube, cutting or rolling means and means for unrolling a film, agooseneck shaper arranged between the extrusion head and the vacuumcalibration tank, means for exerting a first pressure difference betweenthe inside and the outside of the extruded tubular body, and means forexerting a second pressure difference between the inside and the outsideof the tube when same passes through the vacuum calibration tank.

Preferably, the label passes through a gooseneck shaper arranged betweenthe extrusion nozzle and the calibration element. The presence of thegooseneck shaper means that the label does not pass through theextrusion tools, which prevents damage being caused to the decorativefilm. In the present invention, the gooseneck shaper helps to extend theextrusion tools inside the tubular shape formed by the film. The use ofa gooseneck shaper is advantageous for several reasons. It preventscontact between the film and the hot tools, and the compact size of samehelps to reduce the length of the nozzle tool lying inside thegooseneck. The pressure drops, and consequently the pressure generatedby the flow of molten material inside the tool, are greatly reduced.

According to a variant of the invention, the gooseneck shaper, combinedwith a pressure difference between the inside and the outside of thetubular body, helps to associate the tubular body and the decorativefilm inside the gooseneck. One advantage of this variant is the abilityto position the gooseneck shaper close to the extrusion head in order toengage the tubular body as same exits the tool. The tubular body isplaced on the film which slides on the gooseneck and simultaneouslyconveys the tubular body. The compact size of the gooseneck shaper is amajor advantage. This shaper is easily inserted between the extrusionhead and the calibration element.

Another variant of the invention involves extruding a tubular body witha resin comprising blowing agents. These blowing agents cause theinflation of the tubular body in the molten state, thereby bringing theexternal face of the tubular body in the molten state into contact withthe internal face of the film. According to this variant, the contactbetween the outer layer of the tubular body and the inner layer of thefilm is preferably caused by the blowing agents contained in the resin,and not by a pressure difference. Furthermore, the external diameter ispreferably calibrated by the action of the blowing agents, but may alsobe caused by a pressure difference between the inner surface of thetubular body and the outer surface of the film, or by the combination ofthe action of the blowing agents and a pressure difference. This variantof the invention is particularly advantageous for lightening thepackaging without the drawback of the blowing agents adversely affectingthe appearance of same. Indeed, the decorated film that forms the outersurface of the packaging provides the decoration and surface properties,and the use of blowing agents helps to reduce the quantity of resin usedto form the extruded tubular body and to form the inner layer of thepackaging.

The invention is not limited to the depositing of a film on the tubularbody in the molten state. Another variant of the invention involvesdepositing the decorative film on the outer surface of a full extrudedbody including blowing agents. For example, the decorative film isdeposited on the outer surface of an extruded cylindrical body includingblowing agents. The expansion of the cylindrical body at the outlet ofthe extrusion tool causes the inner layer of the film to come intocontact with the outer surface of the extruded body. Simultaneously orsuccessively, the external diameter of the decorated cylindrical body isadjusted by passing the cylindrical body through a gauge and a coolingtank. This variant of the invention is particularly advantageous formaking packaging parts such as the synthetic corks used in glassbottles. The wine market is an important market. The optimization ofthis type of cork may require differentiation of the surface properties(sliding, seal, decoration) and the core properties (contact with wine,elasticity, compression, resistance).

The decorative film may be deposited on extruded bodies with round, ovalor square sections, or sections of a more complex shape.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a prior art method described in patent application WO2007092652, which involves applying a label 17 with no glue to thesurface of the tubular body 13 in a step in which an adhesive layer 15is applied just before assembly of the label 17 on the surface of thetube 13.

FIG. 2 shows a tube 14 from the prior art produced using the methoddescribed in application WO 2007092652. The label 17 is not embedded inthe extruded tubular body 13. The edges 18 of the label 17 cause adiscontinuity in the outer surface of the packaging which adverselyaffects the aesthetics of same.

FIG. 2A shows a cross-sectional partial view of FIG. 2 showing the label17 that is not embedded in the extruded tubular body 13.

FIG. 3 shows the preferred embodiment of the method according to theinvention. This method involves combining extrusion operations withlabeling operations.

FIG. 4 shows a method according to the invention and an example deviceinvolving extruding a tubular body 13 and depositing a decorative film12 onto the surface of said tubular body.

FIG. 5 shows an example device used to bring the decorative film 12 intocontact with the tubular body 13, and to calibrate the external diameterof the tube 14.

FIG. 6 shows a tube 14 obtained using the method described in theinvention. The ends 18 of the decorative film 12 are embedded in thetubular body 13.

FIG. 7 shows a partial cross section of a tube 14 including a decorativefilm 12 on the surface, the ends 18 and 18′ of which are arranged end toend. The ends 18 and 18′ are embedded in the tubular body 13.

FIG. 8 shows a variant of a tube 14 including a decorative film 12 inwhich the ends 18 and 18′ are arranged end to end. According to thisvariant, the ends 18 and 18′ are in contact and the outer surface of thetube 14 forms a continuous smooth surface.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 3 shows the preferred embodiment of the invention, which involvesforming a decorated tube by depositing a decorative film on the surfaceof an extruded tube while the extruded body is in the molten state. Themethod advantageously combines the extrusion operations D, F, G, H and Iwith the labeling operations A, B, C and E.

The extrusion operation D involves forming a tubular body in the moltenstate using known extrusion means. According to the preferredembodiment, these means include an extruder and an extrusion head 24.According to an alternative embodiment, these means include severalextruders and a co-extrusion head. According to the preferredembodiment, said extrusion head 24 is extended by a tubular portionreferred to as the extrusion nozzle 27. The diameter of the nozzle 27 isless than the diameter of the tube to be formed such that the nozzle canbe engaged inside the shaper 20. The extruded resin is outputted throughthe end of the nozzle 27 and forms a parison 13 located inside thetubular shape formed by the decorative film.

Upstream of the extrusion operation D, the labeling operations A, B andC involve respectively unrolling a decorative film placed on a reel (thelabel), then potentially cutting the lateral edges of the decorativefilm in order to fix the label to the diameter of the tube manufactured,and finally forming the film into a tubular shape. The formation of thetubular shape must be compact to enable the extrusion of the tubularbody in the molten state inside the tubular shape formed by thedecorative film.

The operation E involves bringing the outer surface of the tubular bodyin the molten state into contact with the inner surface of thedecorative film. In the preferred embodiment shown in FIG. 3, theoperations C and E are performed sequentially. The contact between thetubular body in the molten state and the decorative film is made afterthe decorative film has been wound around the tubular body. The meansused for the operation C are preferably a gooseneck shaper, whichenables the decorative film to be placed around the tubular body in themolten state while occupying a limited space. The means used for theoperation E, which involves bringing the extruded tubular body intocontact with the decorative film, are a pressure difference ΔP1 betweenthe inside and the outside of the tubular body in the molten state. Thepreferred embodiment for application of this pressure difference is toat least partially plug the tubular body in the molten state and togenerate an air pressure inside the tubular body in order to “inflate”the tubular body in the molten state against the decorative film.According to this embodiment, it may be advantageous to create a slightair leak around the plug in order to create an air cushion between theplug and the tubular body in the molten state. This air cushion preventsthe inner surface of the tube from being marked and helps to prevent theplug from overheating. Another embodiment involves applying a negativepressure in a box arranged about the gooseneck. The diameter of thelabeled tubular body at the output of the gooseneck is substantiallyequivalent to the diameter of the tube manufactured.

An alternative embodiment involves performing the film formationoperation C and the contacting operation E simultaneously. In this case,the extrusion operation D May be performed before or simultaneously withthe formation operation C.

The operation F, which comes after the operations D and E, enables theexternal diameter of the labeled tube to be calibrated. The operation Fis performed by passing the extruded pipe through a calibration elementincluding calibration and cooling means. A pressure difference ΔP2between the inside and the outside of the tube is exerted during theoperation F. This pressure difference presses the outer surface of thetube against the inner surface of the gauge at the time the tube isbeing cooled. According to the preferred embodiment, the pressuredifference ΔP2 is created by a negative pressure in the calibrationelement. Water is usually used to cool the tube, either in the form of abath or in the form of a shower. A major advantage of the method isrelated to the fact that the tribology during the calibration operationis substantially different to the conventional extrusion method. Indeed,in the method according to the invention, the plastic in the moltenstate is no longer in contact with the gauge since the label ispositioned all the way around the tubular body in the molten state. Thisprovides several advantages in addition to the advantages related toon-line decoration:

-   -   Option of increasing production speed without generating faults,    -   Broader range of resins that can be used to manufacture the        tubes.

The operation G is optional. This operation enables the cooling of thetube to be perfected while ensuring a constant diameter. The operation Gis in particular useful if the tube is particularly thick and if thetube has not been sufficiently cooled following the operation F. Duringthe cooling operation G, a pressure difference ΔP3 between the insideand the outside of the tube may be used to keep the diameter of the tubeconstant during cooling. The operation G is commonly used for tubeextrusion in the conventional methods.

The conveyance operation H is similar to the operation used for tubeextrusion. This operation involves conveying the tube using profiledconveyor belts.

The length cutting operation I involves cutting the tube to the desiredlength. In the method according to the invention, the cutting operationmust be synchronized with decoration of the tube.

FIG. 4 shows an example of the method according to the invention and anexample device. This method involves extruding a tubular body 13 anddepositing a decorative film 12 onto the outer surface of said tubularbody in the molten state.

The method includes the extrusion of the tubular body according to themethods known in the plastics industry. FIG. 3 shows the most commonmethod, which involves using an extruder to melt the thermoplasticresin, before shaping same in a tool 24 including a nozzle 27. Accordingto the preferred embodiment, the extruder is arranged perpendicular tothe extrusion axis. The nozzle 27, the diameter of which is less thanthe diameter of the tube manufactured, is engaged inside a shaperreferred to as a gooseneck 20. The operation to extrude the tubular body13 from the end of the nozzle 27 is located close to the downstreamportion of the gooseneck 20, i.e. close to the transition from which thedecorative film 12 forms a cylinder.

The method includes the use of a decorative film 12 packed on rolls 19.The decorative film is unrolled in a continuous process at the linearmanufacturing speed of the tube. The decorative film is then formed intoa tubular shape about the extruded tubular body in the molten state 13using a gooseneck shaper 20. One advantage of the preferred embodimentof the invention is related to the fact that the film 12 is completelyseparated from the extrusion and tooling unit 24, which helps to preventthe film 12 being subjected to high temperatures and to prevent thedecoration from being damaged. The gooseneck 20 may be very small and isinserted between the extrusion device 24 and the calibration and coolingelement 22, 21 of the tube 14. In a preferred embodiment, a gooseneckshaper is used.

When the decorative film 12 enters the gooseneck shaper 20, the innersurface of the decorative film may move close to the wall of theextrusion nozzle 27 and be heated by the radiation from the surface ofthe extrusion nozzle. Depending on the type of film used, it may beadvantageous to use the radiation to preheat the inner surface of thefilm 12 before contact is made with the extruded material. Conversely,it may be necessary to protect the decorative film from the radiationfrom the extrusion nozzle to prevent the decoration from being damaged,for example. The radiation from the extrusion nozzle 27 may be limitedby altering the radiating surface of said nozzle.

According to the preferred embodiment of the invention illustrated inFIG. 5, the tubular body in the molten state and the decorative filmcome into contact with one another at the outlet of the gooseneck whenthe decorative film forms a cylindrical shape. This contact is caused bya pressure difference ΔP1 between the inside and the outside of thetubular body in the molten state. According to this preferredembodiment, a positive pressure is created inside the tubular body inthe molten state 13 using a plug 29 that at least partially obstructsthe internal section of said extruded tubular body. According to thepreferred embodiment, the plug 29 includes flexible portions 31 thatprovide an at least partial seal with the wall of the tubular body inthe molten state 13. According to the invention, said flexible portionsyield slightly under the effect of the pressure, which results in thecreation of an air cushion and a small downstream leak between the plug29 and the wall of the tubular body. Said plug is attached to the end ofa blow pipe 28, which is preferably cooled and attached to the extrusionhead 24. The downstream air leak 32 has a secondary effect of coolingthe inner surface of the tubular body.

An alternative embodiment of the invention involves creating a secondair leak through the extrusion head, referred to as the upstream leak33. The flow rate of the upstream leak is precisely adjusted and enablesthe process to be stabilized, in particular the contact between thetubular body and the decorative film.

Another alternative embodiment of the invention involves using anexpandable plug 29. An expandable plug facilitates start-up since thelimited section of same facilitates passage of the tubular body.Expansion of the plug enables the downstream leak 32 to be reduced andcontrolled.

Another alternative embodiment of the invention involves using aretractable stowable blow pipe. According to this embodiment, the blowpipe 28 and the plug 29 are positioned inside the extrusion tool at thetime of start-up, which facilitates extrusion of the tubular body. Theblow pipe 28 and the plug 29 are then moved forward gradually into theworking position.

According to the preferred embodiment of the invention, the tubular body13 and the decorative film 12 are assembled when the tubular body 13 isin the molten state, such that the heat from the tubular body melts theinner surface of the decorative film 12. The contact time between themolten tubular body 13 and the decorative film 12 with no active coolingis adjusted to enable optimum welding without damaging the decoration.This time can be adjusted by adjusting the tools to delay passage of thetube through the actively cooled calibration zone. This time isoptimized as a function of the film 12 used (thickness, number oflayers, type of layers, position of decoration within thickness, type ofink, pigments, etc.) and of the tubular body 13 (thickness, number oflayers, type of layers). In general, this time is very short and theactive cooling by the outer surface of the tube 14 may be activatedrapidly following assembly of the tubular body and the decorative film.According to the preferred embodiment, the cooling of the outer surfaceof the tube 14 begins from the time the tube 14 enters the gauge, whichhelps to safeguard the print quality of the decorative film. Accordingto the preferred embodiment of the invention, the outer surface of thedecorative film is not melted during manufacture of the tube 14. Inparticular, the decorated surface is kept at a temperature of at leastless than the melting temperature of the supporting layer or less thanthe degradation temperature of the inks or pigments. Preferably, thegooseneck 20, which is upstream of the calibration and cooling element22, 21, is also cooled or temperature-regulated using a water circuit.

During the operation to bring the tubular body in the molten state intocontact with the decorative film, the tubular body in the melted stateis “inflated” as a result of the pressure difference ΔP1 between theinside and the outside of the tubular body in the molten state. Aftercontact has been made, the tubular body is conveyed at the speed ofmovement of the decorative film. Generally, the tubular body undergoesradial and axial stretching between the outlet of the extrusion nozzle27 and the time contact is made. This stretching effect may be used toadjust the thickness of the tubular body and to stabilize the process.

According to the preferred embodiment of the invention, the externaldiameter of the tube 14 formed by the tubular body in the molten state13 and the decorative film 12 is calibrated by passing said tube 14through the calibration element 22 and by the simultaneous action of apressure difference exerted between the inner surface and the outersurface of the tube 14. This pressure difference occurs when the tube 14enters the calibration element 22 and causes the outer surface of thetube 14 to be pressed against the inner surface of the calibrationelement 22. The outer surface of the decorative film that has not beenmelted is then in contact with the surface of the gauge. In order tolimit the friction between the outer surface of the film and thecalibration tools, it may be advantageous to create a film of waterbetween the calibration tools and the outer surface of the film.

The relative position of the plug 29 in relation to the calibrationelement 22 and to the cooling tank 21 makes it possible to determine thecontact and calibration zones. If the plug 29 is located upstream of thecalibration element 22, the pressure difference AP1 created by the plug29 creates a contact zone located upstream of the calibration tank. Thepressure difference ΔP2 in the calibration element 22 enables theexternal diameter of the tube 14 to be calibrated. If the plug islocated inside the calibration element 22, there is a contact zone witha pressure difference ΔP1, then a calibration zone for the externaldiameter with a pressure difference (ΔP1+ΔP2), and finally a calibrationzone for the external diameter with a pressure difference ΔP2. Therelative position of the plug 29 in relation to the calibration element22 is adjusted as a function of the decorative film and of the materialextruded.

The preferred embodiment of the invention involves using at least onefirst pressure difference ΔP1 to ensure contact between the decorativefilm 12 and the tubular body in the molten state 13 and a secondpressure difference ΔP2 to calibrate the external diameter of the tube14. This arrangement is particularly advantageous for stopping andstarting the line and for the precision of the calibration of theexternal diameter of the tube.

According to another embodiment of the invention, a single pressuredifference ΔP1 is used to perform the contact and calibrationoperations. In this variant, a blow pipe 28 that is long enough tomaintain the diameter of the tube during hardening under the effect ofcooling of the extruded material is used. This embodiment isadvantageously combined with a retractable stowable blow pipe 28.

According to another embodiment of the invention, a single pressuredifference ΔP2 is used. This embodiment may advantageously be used ifblowing agents are added to the extruded material. According to thisembodiment, the addition of blowing agents to the extruded materialcauses contact to be made between the tubular body 13 and the label 17while the pressure difference ΔP2 enables the diameter of the tube to becalibrated.

A specific feature of the invention is that the friction surface of thetube 14 in the calibration tools is formed by the outer surface of thedecorative film 12, which is not in the molten state. This helps tofacilitate the calibration operation for the external diameter of thetube. The tribological properties between the inner surface of the gaugeand the outer surface of the tube are changed radically in relation to aconventional extrusion operation. The method thereby enables the use ofnew extruded materials or increased extrusion speeds.

FIG. 6 shows the tubes 14 obtained using the method. The decorative film12 forms all or part of the outer surface of the tube 14. The detail 6Ashows the embedding of the end 18 of the decorative film in the wall ofthe tubular body 13. The outer surface of the tube 14 is continuousaround the end of the decorative film 12. The label 17 is thin comparedto the thickness of the tubular body 13.

FIGS. 7 and 8 show the embodiment of the invention with a label aroundthe entire periphery of the tube.

FIG. 7 shows a first example embodiment of a 360° decoration of the tubewhere the ends 18 and 18′ of the label 17 are arranged end-to-end andslightly spaced apart. The spacing of the ends of the label 17 may berelated to the precision of the lateral cut of the label 17. Smallspaces 25 between the ends 18 and 18′ that are less than 100 μ andinvisible to the naked eye are sometimes obtained. The space 25 isfilled by the resin forming the tubular body 13, thereby creating anouter surface of the tube 14 that is smooth and has no discontinuitiesaround the ends 18 and 18′.

FIG. 8 shows a second embodiment in which the ends 18 and 18′ of thelabel 17 are arranged end-to-end and in contact with one another. Inthis arrangement, there is continuity in the decorative film and theouter surface of the tube 14. Since the label 17 is thin compared to thethickness of the tubular body 13, the ends 18 and 18′ are imperceptible.This embodiment is particularly advantageous with 360° decoration or toensure continuity of the barrier properties if the barrier layer iscarried by the label 17. This second embodiment may require lateralcutting means for the label 17 positioned upstream of the gooseneck 20.These cutting means ensure a precise adjustment of the width of thedecorative film to achieve the end-to-end positioning shown in FIG. 8.

Another example embodiment of the invention involves forming an overlapbetween the ends 18 and 18′ of the decorative film. This embodiment isparticularly advantageous if the lower surface of the film 12 can bewelded to the upper surface of same. Advantageously, the overlap iswelded during the contact operation E and the calibration/coolingoperation F. According to this preferred embodiment, the overlap iswelded by the heat provided by the extruded tubular body in the moltenstate. An alternative embodiment involves adding a preheating operationbefore the operation E or an overlap-welding operation before, at thesame time as or after the operation E.

In order to strengthen the tubular body about the ends and 18′ of thedecorative film, another example embodiment of the invention involvesincreasing the thickness of the tubular body at the joining point of theends of the film. This local thickness increase in the tube ensures thatthe tube is uniformly strong about the entire circumference of same.

Another example embodiment of the invention involves adding areinforcing strip between the decorative film 12 and the tubular body 13that joins the ends of the decorative film. Advantageously, thereinforcing strip is welded by the heat provided by the tubular body 13in the molten state. If necessary, a preheating operation or a weldingoperation may be added to attach the reinforcing strip to the internalface of the film 12.

The extruded or co-extruded tubular body 13 is usually made of athermoplastic resin from the polyolefin family (such as linearlow-density polyethylene, low-density polyethylene, high-densitypolyethylene, polyethylene blends, polypropylene), but the invention isnot limited to the use of the aforementioned resins. For example, themultilayer structure with an ethylene vinyl alcohol resin as an oxygenbarrier and a polyolefin resin is commonly used to improve the barrierperformance of the packaging. The tubular body 13 accounts for at least70% of the thickness of the tube 14, and preferably at least 80% of thethickness of the tube 14.

The label 17 forms at least a portion of the outer surface of the tube14. This decorative film for example enables the packaged product andthe manufacturer to be identified and provides decoration, etc.According to the preferred embodiment, the decorative film is thin. Thedecorative film may be a single layer or multilayer and may be made of awide variety of materials including paper, aluminum and plastic. Thecarrier film may also be made in part from a textile film to providespecific sensory properties. The decorative film 12 includes at leastone layer that enables the decorative film to adhere to the tubular body13 under the effect of the heat provided by said extruded body. Thedecorative film is preferably a single layer. The multilayer structuremay comprise for example polyethylene, polypropylene, polyethyleneterephthalate, polyamide, ethylene vinyl alcohol, paper, aluminum,metallization, silicon oxide or adhesive layers, inter alia. Preferably,the thickness of the decorative film is between 5 and 100 μ, andadvantageously between 10 and 50 μ.

According to the preferred embodiment of the invention, the structure ofthe label 17 has at least one layer with a melting temperature exceeding160° C. and at least one layer of the same type as the tubular body. Thelayer with good thermal stability may for example be made up ofbiaxially oriented polyethylene terephthalate (PET), polyamide (PA),aluminum (Alu) or paper. Example structures of the decorative film for apolyethylene tubular body include PET/PE, PE/PET/PE, PA/PE, Alu/PE,PE/Alu/PE and Paper/PET/PE.

The label 17 may be printed using any known flat printing method, suchas flexography, screen printing, gravure printing, letterpress printing,offset printing, digital printing or a combination of these printingtechnologies. The invention is advantageously combined with digitalprinting for production that requires flexibility and rapid decorationchanges. The print is usually covered by a protective varnish, which mayalso provide gloss or matte effects for example. The choice of varnishis important, in particular the coefficient of friction of same with theshaping and calibration tools.

The invention may advantageously be combined with on-line digitalprinting of the label 17. In this case, the role of decorative film 19shown in FIG. 4 is replaced by a digital printing machine operating insynchrony with the labeling/extrusion line. According to a variant ofthis configuration, one or more lamination operations may also beperformed on-line before the extrusion/decoration process. For example,a lamination operation is required if the print is to be containedwithin the thickness of the decorative film 12. A possible arrangementresulting in a contained printed layer can be achieved using thefollowing steps:

-   -   Unrolling a first undecorated film,    -   Digital printing of the first film,    -   Lamination of a second film on the first film to contain the        print—Decorative film obtained    -   Lateral cutting of the edges of the decorative film,    -   Extrusion/decoration process.

The decorative film 12 may be printed on the front or on the back suchthat the print is found on the surface of the tube 14 or containedwithin the thickness of the tube. The printing is advantageous forproviding complex decorations at low cost since the decoration operationis performed flat on a thin film.

The invention is particularly advantageous for providing tubes withhigh-quality decoration at low cost.

The invention is particularly advantageous for improving the sensoryproperties of the tubes by providing a decorative film with a surfacelayer having a particular “feel”. These properties are provided forexample by a matte biaxially oriented polypropylene film or a textilefilm.

The invention is particularly advantageous since it enables thefunctionality of the packaging to be altered by changing the decorativefilm. These functions may be aesthetic (decoration), sensory (feel),technical (barrier properties) or informative (information onpackaging).

The invention is particularly advantageous since the decorative filmforms an integral part of the packaging. The decorative film isincorporated into the structure of same and contributes to theproperties of same.

The invention is not limited to the example multilayer structuresmentioned in the text. It is obvious to the person skilled in the artthat the invention enables the number of possible structures to beincreased and a range of different materials to be used (plastic, paper,aluminium, etc.).

By default, the invention enables the manufacture of undecorated tubularbodies incorporating a surface film. This variant may be used morespecifically to improve the mechanical, barrier or sensory (feel)properties of the tubes.

The invention may be used in the field of packaging primarily to providedecoration but also in technical fields to improve mechanical or barrierproperties. An advantageous embodiment of the invention involvesproviding the barrier and the decoration using the film. The multilayerfilm that provides the barrier and the decoration is associated with amultilayer extruded body, which helps to simplify the extrusion device.

When extruding a difficult product, the invention may be used to reduceproduction costs while increasing production speeds.

A first variant of the invention involves the following successiveoperations:

-   -   Welding of a first tubular body from a single-layer or        multilayer film,    -   Extrusion of a second tubular body in the molten state on said        first tubular body,    -   Simultaneous depositing of the label on the outer surface of the        second tubular body using the method according to the invention.

A second variant of the invention involves containing the label withinthe wall of the tube. To do so, the following operations are carriedout:

-   -   Extrusion of a first tubular body in the molten state,    -   Simultaneous depositing of the label on the outer face of the        first tubular body using the method according to the invention,    -   Extrusion of a second tubular body and depositing of said second        tubular body in the molten state on the outer face of the label.

The second tubular body in the molten state is deposited on the outerface of the label, preferably when the first tubular body has at leastpartially cooled.

A third variant of the invention involves attaching a film to the outersurface of and extruded tubular body incorporating blowing agents. Thefollowing method is used:

-   -   Extrusion of the tubular body in the molten state from a resin        incorporating blowing agents,    -   Depositing of the film about the tubular body using a gooseneck        shaper,    -   Bringing the outer surface of the tubular body into contact with        the inner face of the film by inflating the tubular body using        the blowing agents,    -   Calibration of the tubular body and cooling.

A fourth variant of the invention is used to manufacture cylindricalbodies incorporating blowing agents and a surface film. The followingmethod is used:

-   -   Extrusion of a cylindrical body in the molten state from a resin        incorporating blowing agents,    -   Depositing of the film about the cylindrical body using a        gooseneck shaper,    -   Bringing the inner surface of the film into contact with the        outer surface of the cylindrical body by inflating the        cylindrical body using the blowing agents,    -   Calibration of the cylindrical body and cooling.

The blowing agents used may be physical or chemical blowing agents. Thephysical blowing agents mixed with the polymer are for example carbondioxide gas or nitrogen gas in which the change of state (liquid to gas)expands the polymer in the molten state. The chemical blowing agents maybe azodicarbonamide or azobisformamide. The advantage provided by theinvention when making expanded cylindrical or tubular bodies is thecombination of the surface properties and decoration provided by thefilm and the lightening properties provided to the core by the blowingagents.

1-9. (canceled)
 10. An extruded and labelled packaging tube, thepackaging tube manufactured by the steps of: forming a partially orfully tubular label from a film; introducing the tubular label into acalibration device; extruding a tubular body on a side of a concavesurface of the tubular label; and bringing an external surface of thetubular body into contact with the concave surface of the tubular label,wherein the step of extruding is performed in the calibration device,and wherein the film is welded or embedded in a wall of the tubularbody.
 11. The extruded and labelled packaging tube of claim 10, whereinthe tubular body includes a resin having a blowing agent to cause thetubular body to inflate either in a molten state or after the step ofextruding.
 12. The extruded and labelled packaging tube of claim 10,wherein the tubular label includes two ends which are arranged end toend or overlap or are spaced apart by a space, the space being filledwith the resin that forms the tubular body.
 13. The extruded andlabelled packaging tube of claim 10, wherein a thickness of the tubularbody is increased at a joining point of ends of the film.
 14. Theextruded and labelled packaging tube of claim 10, wherein a reinforcingstrip is added that joins ends of the film.
 15. The extruded andlabelled packaging tube of claim 10, the method further comprising thestep of: enclosing the tubular label within a wall of the packaging tubeby extruding a second tubular body and applying the second tubular bodyin a molten state to the external surface of the tubular label.
 16. Theextruded and labelled packaging tube of claim 10, wherein the tubularlabel has a monolayer or multilayer structure.
 17. The extruded andlabelled packaging tube of claim 16, wherein the multilayer structureincludes at least one of polyethylene, polypropylene, polyethyleneterephthalate, polyamide, ethylene vinyl alcohol, paper, aluminum,metallization or silicon oxide layers, and adhesive layers.
 18. Theextruded and labelled packaging tube of claim 10, wherein the tubularlabel is printed.
 19. An extruded and labelled packaging tubecomprising: a tubular body made of thermoplastic resin; and a tubularlabel having a concave surface, the concave surface being in contactwith the tubular body by extrusion of the thermoplastic resin againstthe concave surface of the tubular label.
 20. The extruded and labelledpackaging tube of claim 19, wherein the tubular label is surrounding thetubular body such that the two ends of the tubular label overlap eachother.
 21. The extruded and labelled packaging tube of claim 19, whereinthe tubular label is partially surrounding the tubular body such thatthe two ends of the tubular label are spaced apart by a space, the spacebeing filled with resin that forms the tubular body.
 22. The extrudedand labelled packaging tube of claim 21, wherein an outer surface of thetubular body and the partially surrounding tubular label form acontinuous smooth tubular surface with no discontinuities.
 23. Theextruded and labelled packaging tube of claim 19, wherein the contactbetween an outer surface of the tubular body and an inner surface of thetubular label is caused by blowing agents contained in a resin thatforms the tubular body.
 24. The extruded and labelled packaging tube ofclaim 19, wherein the tubular label has a multilayer structure.
 25. Theextruded and labelled packaging tube of claim 24, wherein the multilayerstructure includes at least one of polyethylene material, polypropylenematerial, polyethylene terephthalate (PET) material, polyamide material,ethylene vinyl alcohol material, paper, aluminum, metallization layer,silicon oxide layer, and an adhesive layer.
 26. The extruded andlabelled packaging tube of claim 19, wherein thermoplastic resin of anouter surface of the tubular body is fused to the concave surface of thetubular label.
 27. The extruded and labelled packaging tube of claim 19,wherein the tubular label is surrounding the tubular body such that thetwo ends of the tubular label are in contact with each other, thetubular label forming a barrier layer.